Nowadays the summit is ascended by an average of 20,000 mountaineer-tourists each year. It could be considered a technically easy, yet arduous, ascent for someone who is well-trained and acclimatized to the altitude. From l'"Aiguille du Midi (where the cable car stops), Mont Blanc seems quite close, being 1,000 m (3,300 ft) higher. But while the peak seems deceptively close, La Voie des 3 Monts route (known to be more technical and challenging than other more commonly used routes) requires much ascent over two other 4,000 m mountains, "Mont Blanc du Tacul and "Mont Maudit, before the final section of the climb is reached and the last 1000 m push to the summit is undertaken.

Each year climbing deaths occur on Mont Blanc, and on the busiest weekends, normally around August, the local rescue service performs an average of 12 missions, mostly directed to aid people in trouble on one of the normal routes of the mountain. Some routes require knowledge of high-altitude mountaineering, a guide (or at least an experienced mountaineer), and all require proper equipment. All routes are long and arduous, involving delicate passages and the hazard of rock-fall or avalanche. Climbers may also suffer "altitude sickness, occasionally life threatening, particularly if they do not "acclimatize to it.[5][6]

1832 Map of the Kingdom of Sardinia showing an administrative border passing through the summit of Mont Blanc. This was the same map annexed to the 1860 treaty to determine the current border between France and Italy.

Since the "French Revolution, the issue of the ownership of the summit has been debated. From 1416 to 1792, the entire mountain was within the "Duchy of Savoy. In 1723 the Duke of Savoy, "Victor Amadeus II, acquired the "Kingdom of Sardinia. The resulting state of Sardinia was to become preeminent in the "Italian unification.[8] In September 1792, the French revolutionary "Army of the Alps under "Anne-Pierre de Montesquiou-Fézensac seized "Savoy without much resistance and created a "department of the "Mont-Blanc. In a "treaty of 15 May 1796, "Victor Amadeus III of Sardinia was forced to cede Savoy and "Nice to France. In article 4 of this treaty it says: "The border between the Sardinian kingdom and the departments of the French Republic will be established on a line determined by the most advanced points on the "Piedmont side, of the summits, peaks of mountains and other locations subsequently mentioned, as well as the intermediary peaks, knowing: starting from the point where the borders of "Faucigny, the "Duchy of Aoust and the "Valais, to the extremity of the glaciers or Monts-Maudits: first the peaks or plateaus of the Alps, to the rising edge of the Col-Mayor". This act further states that the border should be visible from the town of "Chamonix and "Courmayeur. However, neither the peak of the Mont Blanc is visible from Courmayeur nor the peak of the Mont Blanc de Courmayeur is visible from Chamonix because part of the mountains lower down obscure them.

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A Sardinian Atlas map of 1869 showing the summit lying two thirds in Italy and one third in France.[9]

After the Napoleonic Wars, the "Congress of Vienna restored the King of Sardinia in Savoy, Nice and Piedmont, his traditional territories, overruling the 1796 Treaty of Paris. Forty-five years later, after the "Second Italian War of Independence, it was replaced by a new legal act. This "act was signed in "Turin on 24 March 1860 by "Napoleon III and "Victor Emmanuel II of Savoy, and deals with the annexation of "Savoy (following the French neutrality for the plebiscites held in Tuscany, Modena, Parma and Romagna to join the Kingdom of Sardinia, against the Pope's will). A demarcation agreement, signed on 7 March 1861, defined the new border. With the formation of Italy, for the first time Mont Blanc was located on the border of France and Italy.

The 1860 act and attached maps are still legally valid for both the French and Italian governments.[10] One of the prints from the 1823 Sarde Atlas[11] positions the border exactly on the summit edge of the mountain (and measures it to be 4,804 m (15,761 ft) high). The convention of 7 March 1861 recognises this through an attached map, taking into consideration the limits of the massif, and drawing the border on the icecap of Mont Blanc, making it both French and Italian. Watershed analysis of modern "topographic mapping not only places the main summit on the border, but also suggests that the border should follow a line northwards from the main summit towards "Mont Maudit, leaving the southeast ridge to "Mont Blanc de Courmayeur wholly within Italy.

Although the Franco-Italian border was redefined in both 1947 and 1963, the commission made up of both Italians and French ignored the Mont Blanc issue. In the early 21st century, administration of the mountain is shared between the Italian town of "Courmayeur and the French town of "Saint-Gervais-les-Bains, although the larger part of the mountain lies within the commune of the latter.

The first professional scientific investigations on the summit were conducted by the "botanist-"meteorologistJoseph Vallot at the end of the 19th century. He wanted to stay near the top of the summit, so he built his own permanent cabin.

In 1890, "Pierre Janssen, an "astronomer and the director of the Meudon astrophysical observatory, considered the construction of an observatory at the summit of Mont Blanc. "Gustave Eiffel agreed to take on the project, provided he could build on a rock foundation, if found at a depth of less than 12 m (39 ft) below the ice. In 1891, the Swiss surveyor Imfeld dug two 23 m (75 ft) long horizontal tunnels 12 m (39 ft) below the ice summit but found nothing solid. Consequently, the Eiffel project was abandoned.

Despite this, the observatory was built in 1893. During the cold wave of January 1893 a temperature of −43 °C (−45 °F) was recorded on Mont Blanc, being the lowest ever recorded there.

Levers attached to the ice supported the observatory. This worked to some extent until 1906, when the building started leaning heavily. The movement of the levers corrected the lean slightly, but three years later (two years after Janssen’s death), a crevasse started opening under the observatory. It was abandoned. Eventually the building fell, and only the tower could be saved "in extremis.[12]

In 1946 a drilling project was initiated to carve a tunnel through the mountain. The Mont Blanc tunnel would connect "Chamonix, "France and "Courmayeur, "Italy and become one of the major trans-Alpine transport routes between the two countries. In 1965 the tunnel opened to vehicle traffic with a length of 11,611 metres (7.215 mi).[16]

In 1999 a transport truck caught fire in the tunnel beneath the mountain. In total 39 people were killed when the fire raged out of control. The tunnel was renovated in the aftermath to increase driver safety, reopening after three years.[17]

In general it is not advised for children to go above 3000 meters until their adolescence.[18] However, youngest person to climb Mont Blanc record set in 2009 by 10 year Asher Silver ("UK)[19] challenges parents.

In July 2014 an "American entrepreneur and traveler "Patrick Sweeney attempted to break the record with his nine-year-old son P.J. and 11-year-old daughter Shannon. They were caught in "avalanche, luckily escaped death and decided not to pursue their attempt.[19][18]

In August 2014 an unknown "Austrian climber with his 5-year-old son were intercepted by "mountain gendarmes at 3200 meters and forced to turn around.[20]

In August 5th 2017 9-year old "Hungarian twins and their mother were rescued from 3800 meters by helicopter while their father and family friend continued their summit attempt.[21]

The summit of Mont Blanc is a thick, perennial ice and snow dome whose thickness varies. No exact and permanent summit elevation can therefore be determined, though accurate measurements have been made on specific dates. For a long time its official elevation was 4,807 m (15,771 ft). In 2002, the "IGN and expert surveyors, with the aid of "GPS technology, measured it to be 4,807.40 m (15,772 ft 4 in).

After the "2003 heatwave in Europe, a team of scientists re-measured the height on 6 and 7 September. The team was made up of the glaciologist Luc Moreau, two surveyors from the GPS Company, three people from the "IGN, seven expert surveyors, four mountain guides from "Chamonix and "Saint-Gervais and four students from various institutes in France. This team noted that the elevation was 4,808.45 m (15,775 ft 9 in), and the peak was 75 centimetres (30 in) away from where it had been in 2002.

After these results were published, more than 500 points were measured, to assess the effects of climate change and the fluctuations in the height of the mountain at different points. Since then, the elevation of the mountain has been measured every two years.

The interpretation that the heatwave had caused this fluctuation is disputed because the heatwave is known not to have significantly affected the glaciers above 4,000 m (13,000 ft). The height and position of the summit could have been moved by general glacial forces. At this elevation, the temperatures rarely rise above 0 "°C (32 "°F). During the summer of 2003, the temperature rose to 2 °C (36 °F), and even 3 °C (37 °F), but this would not have been enough for the ice to melt that amount.

The summit was measured again in 2005, and the results were published on 16 December 2005. The height was found to be 4,808.75 m (15,776 ft 9 in), 30 cm (12 in) more than the previous recorded height. The rock summit was found to be at 4,792 m (15,722 ft), some 40 m (130 ft) west of the ice-covered summit.[22]

In 2007 the summit was measured at 4,807.9 m (15,774 ft) and in 2009 at 4,807.45 m (15,772 ft).[2] In 2013 the summit was measured at 4,810.02 m (15,781 ft) and in 2015 at 4,808.73 m (15,777 ft).[1] From the summit of Mont Blanc on a clear day, the "Jura, the "Vosges, the "Black Forest and the "Massif Central mountain ranges can be seen, as well as the principal summits of the Alps.

The Mont Blanc Massif averages nearly 100 fatalities a year. A published estimate suggests there have been 6,000-8,000 alpinist fatalities in total, more than on any other mountain.[23]:208 Several classic climbing routes lead to the summit of Mont Blanc:[24][25]

The historic itinerary through the Grand Mulets, which is most frequently traversed in winter by ski, or in summer to descend to Chamonix.

The normal Italian itinerary is also known as La route des Aiguilles Grises. After crossing the "Miage Glacier, climbers spend the night at the "Gonella refuge. The next day one proceeds through the Col des Aiguilles Grises and the Dôme du Goûter, concluding at L'arête des Bosses (Bosses ridge).

The Miage — Bionnassay — Mont Blanc crossing is usually done in three days, and has been described as a truly magical expedition of ice and snow aretes at great altitude.[23]:199 The route begins from Contamines-Montjoie, with the night spent in the Conscrits cabin. The following day, the Dômes de Miages is crossed and the night spent at the Durier cabin. The third day proceeds over "l'Aiguille de Bionnassay and the Dôme du Goûter, finally reaching the summit of Mont Blanc via the Bosses ridge.

Recent temperature rises and heatwaves, such as that of summer 2015, have had significant impacts on many climbing routes across the Alps, including those on Mont Blanc. For example, in 2015, the Grand Mulets route, previously popular in the 20th century, was blocked by virtually impenetrable crevasse fields, and the Gouter Hut was closed by municipal decree for some days because of very high stonefall danger, with some stranded climbers evacuated by helicopter.[27]

30 May 2003 (2003-05-30): "Stéphane Brosse and "Pierre Gignoux tried to beat the record by ski-walking. They went up in 4 hours and 7 minutes, and came back down in 1 hour and 8 minutes. In total they did the ascent and descent in 5 hours and 15 minutes.

13 August 2003 (2003-08-13): Seven "French paraglider pilots landed on the summit. They reached a peak altitude of 5,200 m (17,100 ft), thanks to the hot weather conditions, which provided strong hot air currents. Five had left from Planpraz, one from "Rochebrune at "Megève and the last one from "Samoëns.

8 June 2007 (2007-06-08): Danish artist "Marco Evaristti draped the peak of Mont Blanc with red fabric, along with a 20-foot (6.1 m) pole with a flag reading "Pink State". He had been arrested and detained earlier on 6 June for attempting to paint a pass leading up to the summit red. His aim was to raise awareness of environmental degradation.[29]

13 September 2007 (2007-09-13): A group of 20 people set up a hot tub at the summit.[30]

19 August 2012 (2012-08-19): Fifty paraglider pilots landed on the summit, beating the previous record of 7 top landing pilots, set in 2003. This included the second ever tandem landing on the summit.[31]

11 July 2013 - "Kilian Jornet beat the fastest overall time for ascent and descent with 4 hours 57 minutes and 40 seconds.[32][33]

La Terre, son visage, is a documentary by Jean-Luc Prévost and published by Édition Société national de télévision française, released in 1984. It is part of the Haroun Tazieff raconte sa terre, vol. 1 series. In it he talks about the west-east crossing of Mont Blanc.

The Mont Blanc massif is being put forward as a potential "World Heritage Site because of its uniqueness and its cultural importance, considered the birthplace and symbol of modern mountaineering.[34] It would require the three governments of "Italy, "France and "Switzerland to make a request to "UNESCO for it to be listed.

Mont Blanc is one of the most visited tourist destinations in the world, and for this reason, some view it as threatened.["citation needed] Pro-Mont Blanc (an international collective of associations for the protection of Mont Blanc) published in 2002 the book Le versant noir du mont Blanc (The black hillside of Mont Blanc), which exposes current and future problems in conserving the site.[35]

In 2007, Europe's two highest toilets (at a height of 4,260 metres, 13,976 feet) were taken by helicopter to the top of Mont Blanc. They are also serviced by helicopter. They will serve 30,000 skiers and hikers annually, helping to alleviate the discharge of urine and faeces that spreads down the mountain face with the spring thaw, and turns it into 'Mont Marron'.[36]

^Although "Mount Elbrus is normally considered the highest mountain in Europe, the latter continent is part of the "Eurasian land mass, which culminates at Mount Everest (lowest col between Mont Blanc and Mount Elbrus: 113 m [1]; lowest col between Mount Elbrus and Mount Everest: 901 m [2]).

^the prominence of 4,696 m for Mont Blanc is taken from the "Ultras Project" (peaklist.org), "List compiled 2004 by Petter Bjørstad, Jonathan de Ferranti, Eberhard Jurgalski, Vasja Kavcic and Aaron Maizlish". A footnote to this entry at peaklist.org r (Citation). The Mont Blanc key saddle has been identified in Northern Russia near "Ozero Onezhskoye." See also "list of Alpine peaks by prominence.